I have been following the recent debate regarding provision of mammography screening in Bermuda from my home far afield. As a Bermudian GP with a particular interest in public health, I have practised in the UK, Bermuda and now Australia, and I have always strongly encouraged appropriate breast screening.

Breasts are an emotive issue, and women understandably want to feel that they are given the best opportunity to protect themselves from one of the most common causes of cancer in women. Everyone will know someone, a family member or a friend who has been affected by breast cancer, and thus the fear that the diagnosis generates is very real and personal.

We will know women who are breast cancer survivors who had their tumours detected through early screening, and this encourages us to ensure that we get our mammograms.

We will also know women who failed to be screened and who had invasive disease at the time of diagnosis, and we wonder how things might have been different if their disease had been picked up earlier.

So when a decision is made to amend the screening interval for mammography, the understandable reaction is shock and disbelief. Why shouldn’t everyone be screened, every year? If mammography can detect cancer, surely it should be performed as frequently as possible, for as many women as possible?

This is the obvious intuitive response, and argument otherwise seems nonsensical.

Why would there be an argument to postpone routine screening, and why should it be done less frequently than yearly?

These are the types of questions that people across the world have struggled to come to terms with over the years.

It is at this point that statistics, large-scale studies and population epidemiology come into play and things become more complicated to understand.

No one wants to be a “statistic”, but here are a few general points to consider:

• Breast cancer prevalence increases with age. The risk is much higher from age 50 in comparison to age 40. This does not mean that younger women do not get breast cancer, but it is much less common.

• Younger women have denser breast tissue. This means that mammograms are more difficult to assess in younger women. This increases the chances of more unnecessary biopsies and tests. In medical terms these are called “false positive” results.

• The ideal screening interval for mammography is debated, but evidence indicates that benefits of screening are maintained when women have mammograms every two years, while harms from unnecessary anxiety, testing and procedures are reduced.

• Screening programmes from country to country vary quite considerably. For example:

United States — yearly screening recommended from age 40 by the American Cancer Society Guidelines (these guidelines are under review).

England — three-yearly screening offered from age 47 to age 73 by the NHS screening programme.

Australia — women invited to screening between 50 and 74, at two yearly intervals. Earlier screens are available from age 40, but these women are not targeted.

US Preventative Services Task Force Recommendations — (which Bermuda proposes to adopt) — two-yearly screening from age 50-74. Early mammograms available to women considered to be at high risk.

You might think that the countries that screen most frequently have the lowest death rates attributable to breast cancer, but that is not necessarily the case.

For example, OECD Health Data from 2011 showed that breast cancer mortality in females was lower for Australian women in comparison with women in the United States.

Many factors influence these statistics, and demonstrate how things are not as simple as “more screening, better results”.

Most countries with screening programmes accept that screening should occur earlier and more frequently for women who are “high risk” for breast cancer, such as those who have a family history in close relatives.

Women with prior disease need an individualised screening regime.

Women need to discuss their family history and additional risk factors with their doctors.

Bermuda is striving to provide a quality health system for its citizens, while also balancing costs.

A responsible government cannot avoid the topic of cost in this discussion. It should be recognised that a change to the mammography screening interval for women who are not in the high-risk group will have cost-saving implications for the health system.

The decision to change the interval has been based on good quality evidence and is in line with other high quality healthcare systems worldwide.

This decision will ensure that funding can be allocated where it can do the most good for all Bermudians.

• Dr Katherine Michelmore is a Bermudian GP now working in New South Wales, Australia